Method of and apparatus for recovering ammonium chlorid



M. E. MUELLER.

TUS FOR RECOVERING AMMONIUM CHLORlD.

METHOD OF AND APPARA APPLICATION FILED JULY 21 Patented July 20, 1920.

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NmuZuDZOU 12E uwesmohn entree srares Parent orFIcE.

MAX E. MUELLER, F YOUNGSTOWN, OHIQ.

' Specification of Letters Patent.

Patented July 2o, 192a,

Application filed July at, is e. Serial an. elast c.

to explained and the best mode in which l have contemplated applyingthat principle, so as to distinguish it from other inventions.

The present improvement relates more particularly to a method ofobtaining ammonium chlorid, and other fixed ammonia salts produced inthe carbonization oil coal, in the form oi a concentrated solution, andthen recovering such ammonium chlorid and my other ammonia salts fromsuch solution.

improvements in apparatus for use in such recovery process are alsocomprehended. As recognized in such standard texts as Wagners Goal GasResiduals (page 9%), the

5 ammonia thus combined has heretofore only been liberated by theaddition of some stronger alkali, lime, in the form of milk of lime,being usually introduced into the solution for this purpose Thisprocess, how- ,ga ever, requires the use oi large quantities of lime,and furthermore the chlorin present is lost. 0n the other hand, todistil from the aqueous condensate from the gas resulting from thecarbonization of coal, only the volatile ammonia contained therein, and

then to recover the ammonium chlorid and other non-volatile ammoniumsalts by con-- centrating the residual liquor by evaporation andcrystallization, involves the evapso oration of such a large volume ofwater that the process is not advantageous.

The object of the present invention accordingly is the provision of amethod whereby the greater portion of the nonvolatile ammoniumsalts,together with only a small proportion of the volatile ammonium salts,may be obtained in a relatively concentrated solution separate and apartfrom the bulky aqueous condensate, which will to hence contain only asmall proportion of such non-volatile ammonium salts. From thisrelatively concentrated solution, ammonium chlorid and other ammoniumsalts may then be readily recovered by the steps 5a presently to be setforth. The invention also has as its object the recovery of the smallproportions of volatile ammonium compounds remaining in the condensate.

To the accomplishment of the foregoing and related ends, the invention,then, consists or the steps and means hereinafter fully described andparticularly pointed out in the claims, the annexed drawing and thefollowing description setting forth in detail certain means and one modeof carrying out the invention, such disclosed means and modeillustrating, however, but one oi" rious ways in which the principleofthe invention may be used.

in said annexed drawing The single figure there appearing is adIagra-mmatic representation of an approved apparatus designed for thecarrying out of my present process.

Referring first bf thus illustrated, the collector main 1 of a numberor" coke ovens or retorts (not shown) is connected through one or morepipes 2 commonly known as the cross-over or foul main, with the cooleror condenser 3 in which the gas collected from such ovens or retort-s iscooled, such gas being drawn through the pipes and cooler in question bymeans of the exhauster or gas pump Before being discharged from theapparatus, the gas passes through a tar extractor 5 where the last ofthe tar is removed thererrom.

Preferably located at a somewhat lower level than condenser 3 and tarextractor 5 1s a tank 6 which is designed to receive and contam amixture of tar and aqueous liquor. Apump 7 having its intake connectedwith said tank is adapted to elevate such mixture of tar and equeousliquor through a branched pipe 8 to collector main 1 and cross-over main2. This mixture, as it collects in the bottom of said mains 1 and 2along with any condensation from the gas that may be added thereto, isreturned again to tank 6 by means of pipes 9 and 9. It will thus be seenthat a circulation of the llquid contents of tank 6 is'maintained bymeans of pump 7 through pipes 8 and 9 and the intervening portions ofmains 1 and 2.

Pipes 9 and 9 are also adapted to be connected through branches 10 and10 of pipe 1f) with a tank 11 whereby a portion of such circulatingliquid can be transferred to said tank and there allowed to stand andseparate, following which the aqueous liquor is transferred to anevaporator (not shown).

all to the apparatus r The aqueous and tarry condensates from thecondenser 3, exhauster 4 and tar extractor .5 are collected by means ofa pipe 12 having suitable branches 12, 12 and 12, and, discharge into aseparating tank 13, where, as in the case of tank 11 such aqueous andtarry portions of the condensate are allowed to separate. The tarryportion of the condensate may then be transferred through pipe 14 totank 6, or by means of a branch pipe 14 direct with the suction line ofpump 7. Similarly a portion of the aqueous condensate from said tank 13maybe transferred by pipe 15 to said tank 6, or through a branch 15direct to the suction line of pump 7, the main portion of such aqueouscondensate being removed from tank 13 through another pipe (not shown);while by means of yet another pipe line 16 having one branch 16connected near the bottom -of tank 11 and another branch 16 connectednear the top of said tank, either aqueous or tarry liquor from said tankcan be returned to tank 6.

The method of operation of the foregoing apparatus, in' carrying out myimproved method or process, may now be set forth as follows, viz. :Tar,carrying with it a small proportion of aqueous condensate, is pumpedfrom tank 6 by pump 7 through pipe 8 to mains 1 and 2. The waterentrained in the tar absorbs from the gas in these mains thenon-volatile. ammonia compounds, while at the same time the heat of thegas evaporates some of such water and also liberates most of thevolatile ammonia present therein. The major portion of the tar, which isthus sprayed into mains 1 and 2, together with the tar thus condensedfrom the gas in these mains, is returned to tank 6. The tempera--' ture,however, of such returned tar will obviously be higher than when thussprayed into said mains, and in order to prevent such temperature fromrising to a point where trouble will result from foaming or boiling, asufficient quantityiof comparatively cool tar which has condensed fromthe gas in cooler 3, exhauster 4 and tar extractor 5, or which 'has beenseparated from the aqueous and tarry mixture in tank 13, is added to thecirculating system through the appropriate pipe connections. If stillfurther cooling of the tar in such circulating system is required, aportion of the aqueous condensate from said tank 13 may be transferredthrough pipe 15.

The volume of tar in the circulating system is maintained approximatelyconstant by removing a portion of the circulating liquid eithercontinuously or intermittently through pipe 10 and transferring same toseparating tank 11 where the tarry and aqueous portions are allowed toseparate out as previously described. The aqueous liquid that thusseparates out contains the amsired further to increase the concentrationof the ammonium salts in this aqueous liquor in tank 11, a portionthereof may be withdrawn through branch 16 of pipe 16 and added to thecirculating system for the p purpose of cooling the tar in tank 6 inplace of similar liquor from tank 13 being used for this purpose. Toavoid the loss of the small proportion of volatile ammonium compounds,the solution, before evaporation, may be neutralized with hydrochloricacid, or the ammonia of such compounds may be recovered from the vaporsfrom the evaporator by any of the usual methods, as for instance, bypassing these vapors through an acid solution.

It .will be seen from the foregoing de scription that I circulatethrough the mains, from which the gas flows from the carbonizingchambers to the coolers or exhausters, either a tarry or an aqueousfluid, or a mixture thereof, which to this extent resembles currentpractice. However, in order to obtain a relatively concentrated solutionof non-volatile salts, I remove this circulating fluid from such gasmains before the gas is cooled to a temperature at which much watervapor condenses from the gas, and I further keep this circulating fluidseparate from the bulk of the aqueous condensate which separates fromthe gas as the latter is further cooled.

In other words, the fluid, usually consisting of a mixture of aqueousand tarry liquors, which is circulated through the gas mains, istransferred only gradually (either continuously or intermittently) tothe tank or reservoir where the tar and aqueous portions are allowed toseparate. Such aqueous portion accordingly will contain a highproportion of non-volatile ammonium salts, and it is commerciallyfeasible to recover these by the ordinary process of evaporation andcrystallization. Instead of replacing the liquid which has beentransferred from the circulating system with a portion of thecondensate, either tarry or aqueous or both, which separates from thegas as the latter is further cooled, water may be substituted of the oneexplained, change being made as regards the steps or mechanism hereindisclosed, provided the means stated by any of the following claims orthe equivalent of such stated means be employed.

my invention may be employed instead,

I therefore particularly point out and distinctly claim as my invention1-- 1. In a method of recovering ammonium chlorid and other fixedammonia salts resulting from the carbonization of coal, the steps whichconsist in repeatedly passing a limited body of aqueous and tarryliquors in contact With the gaseous products of such carbonization,prior to the cooling thereof .and extraction of tar therefrom, thetemperature being kept above that at which much water vapor condensesfromsuch gas, and replacing such liquors gradually with similarffeshliquors from the cooling and tarextraction stages.

2. In a method of recovering ammonium chlorid and other fixed ammoniasalts resulting from the carbonization of coal, the steps which consistin repeatedly passing a limited body of aqueous and tarry liquorsincontact with the gaseous products of such carbonization, prior to the.cooling thereof and extraction of tar therefrom, the temperature beingkept above that at which much water vapor condenses from such gas,withdrawing such liquors gradually as they are added to by condensationfrom such gas, andv at the same time replacing the same gradually withsimilar fresh liquors from the cooling and tar-extraction stages;

3. In apparatus for recovering values from coal gases, the combinationwith the gas main leading to a condenser and tar-extractor, of meansadapted to circulate a mixture of aqueous and .tarry liquors throughsaid main, a storage and separating tank, and connections for divertinga portion of such liquors from said circulating means to said tank.

4. In apparatus for recovering values from coal gases, the combinationwith the gas main. leading to a condenser and tarextractor, of meansadapted to circulate a through said main, a storage and separating tank,connections for diverting a portion of such liquors from saidcirculating means to said tank, and other connections for returningeither aqueous or tarry liquor, as desired, from said tank to saidcirculating means.

5. In apparatus for recovering values from coals gases, the combinationwith the gas main leading to a condenser and tar-extractor, of meansadapted to circulate a mixture of aqueous and tarry liquors through saidmain, a storage and separating tank, connections for diverting a portionof such liquors from said circulating means to said tank, otherconnections for returning either aqueous or tarry liquor, as desired,from said tank to said circulating means, and means adapted to supply tosaid circulating means either aqueous or tarry liquor, as desired, fromsaid condenser and tar-extractor.

6. In a method of recovering ammonium chlorid and other fixed ammoniasalts resulting from the carbonization of coal, the steps which consistin repeatedly passing a limited body of aqueous and tarry liquors incontact with the gaseous products of such carbonization, prior to thecooling thereof and extraction of tar therefrom, the temperature beingkept above that at which much water vapor condenses from such gas, andreplacing such liquors gradually with similar fresh liquors from thecooling and tar-extraction stages, such fresh liquors includingsubstantially all of the tar from the stages in ques tion and onlysuflicient of the aqueous condensate to maintain a suitable temperaturein the circulating liquors.

7. In a method of recovering ammonium chlorid and other fixed ammoniasalts resulting from the carbonization of coal, the steps which consistin repeatedly passing a limited body of aqueous and tarry liquors incontact with the gaseous products of such carbonization, prior to thecooling thereof and extraction of tar therefrom, the temperature beingkept above that at which much water vapor condenses from such gas,withdrawing such liquors gradually as they are added to by condensationfrom such gas, and at the same time replacing the same gradually withsimilar fresh liquors from the cooling and tar-extraction stages, suchfresh liquors including substantially all of the tar from the stages inquestion and only suflicient of the aqueous condensate to maintain asuitable temperature in the circulating 1i uors. I

igned by me, this '15 day of July, 1919. I MAX E. MUELLER.

